Certian layouts of dial markings strike me as "backwards". Examples in the above picture are figures F, G, L, R, U, V and X. These have the frequency markings in a decending to the right mode. What seems more "natural" to me is to have the frequencies ascend to the right, as in figures H, M, N, P, S, T and W. I haven't decided in the case of vertical dials, such as figures A, B, C, D, E, and J.
Complements of "correct" and "backwards" dials could be paired as follows: N and G, H and L, P and F, and slide rule dials M and R. Complements of dials in the vertical direction would be B and J, and C and D.
Of course, it all depends on what way you need twist the shaft of the tuning capacitor to get decreasing capacitance (thus increasing frequency). For a cap that you need twist clockwise to increase received frequency, I'd pick a dial like that in Figures P and not G or V. For a cap you need twist counterclocwise to increase frequency, I'd pick a dial like figure N and not F or X, though J is acceptable because it is vertical. Also W is also good, if you have to have a moving pointer, arrange the frequencies below the dial. Dial X got it backwards.
In the case of slide rule dials, it depends how the dial cord is strung. The most common are M and R, with moving pointer and stationary freqs. My perferred one is M and not R. A fairly rare dial is the scrolling slide rule: stationary pointer and moving frequencies, like figures E and U. U is actually a thumbwheel, but could be considered as scrolling frequencies. The dial in figure U is backwards, though.
One problem that shows up in dual band radios with circular dials such as fig K is that when one of the band's frequencies are "correct", the other band is "backwards". However, a nice solution to this problem is to mark the calibrations and dial like figure A. As I haven't selected a preference for vertical dials, this is a nice method. Fig A shows a set of moving pointers and stationary frequencies. The reverse, moving freqs and stationary pointers would also work for me. Another solution is shown in fig S, just put both bands on the same side of the shaft of the dial. Some single band radios show two calibrations, one set is frequencies, the other wavelengths. See figures H (correct), and L (backwards).
To the left is a drawing of a style of a dualband dial that I've never seen on a real radio (except for a Silvertone). A combination of styles. Stationary pointer on top, stationary frequencies on the bottom, moving frequencies on top, moving pointer on bottom. This way, the frequency markings are both ascending to the right. The Silvertone has the pointers and ascending frequency markings the other way around. The AM frequency numbers on the stationary background are the usual AM calibrations 55 thru 160. And the FM calibrations on the moving dial range from 88 to 108.
Every dial except T above has the frequencies at
the high end scrunched up together. Figure
T is a linear spacing marking, mainly by
making the tuning shaft off center of the
dial.
A similar mechanism, except this one uses a planetary drive shaft. I found it in my father's old junk box of pre-war
radio stuff, around the 1930's.